It is often desired to have a bag constructed so that it can be used not only for the intended purpose but also for an alternative purpose. For example, a nursing bag for travelling purposes can be used as a container for the necessary equipment for nursing babies and also as a nursing table. The pieces of different types of games may be stored in a container which is opened and made flat to be used as a playing board.
A simple bag comprising a folded integral piece of sheet material will not form a defined bottom but will rather have a pocket-like design. When transporting different items in such a bag the items in question will tend to be accumulated in the fold of the pocket. It is also more difficult to push down a large object into such a bag. On the other hand, if the bottom, integral with the bag, is constructed with some sort of reinforcement a playing mat formed by such a bag will no longer be flat when spread out on the ground, on a floor, or on another flat support.